MILWAUKEE (WKOW) -- A Democrat challenging Gov. Scott Walker in the upcoming election is making his presence known at the Republican Party of Wisconsin's annual convention.

Businessman Andy Gronik is sponsoring a rolling billboard outside the Wisconsin Center, criticizing the governor. Gronik says he wanted to send a different message than the one the governor is giving at the GOP convention.

"We're taking the fight to him. We have a mobile billboard ... that's circling this building like a shark and it's bringing forward the kind of special interest money that Scott Walker's been taking his entire time in office," said Gronik.

Gronik held a press conference Saturday morning to show off his "Follow the Money" billboard.